In 1859, gold was discovered along Cherry Creek in Denver, and set in motion an epic transformation of Colorado and the West. The "Great American Desert" soon became an irrigated garden of abundance, in spite of climatic challenges. In 1870, the first large-scale community irrigation system in America was developed by settlers of the Union Colony — today Greeley, Colorado. An irrigation ditch was dug from the Cache la Poudre River to the new town, called the Greeley Irrigation Company Ditch. The first ditch rider was David Boyd, a graduate of the University of Michigan. His job was to plug gopher holes and allocate water among the 200 parcels of flood-irrigated land along the ditch. The first year was "ash dry" and caused many delivery problems because the average annual precipitation was only 12 to 14 inches (30 to 36 cm annually).
A few summers later, in 1874, it was just as hot and dry, and Cache la Poudre River flows were even less than in 1870. So, the Union Colony irrigators rode upstream on horses to investigate. To their horror, new irrigation canals were diverting all of the Poudre River water to fields of the new town of Fort Collins. Heated words were exchanged between irrigators because the downstream "senior" irrigators knew the Union Colony settlement was doomed if the upstream "junior" diverters continued to take water from the dwindling river. The problem was not resolved, so a meeting was called at a neutral schoolhouse midway between the two communities.
The meeting was lively, to say the least. Most of the irrigators present were Civil War veterans, since the conflict had just ended. General Robert Cameron of Brooklyn, New York, one of the founders of the Union Colony settlement, and also of Fort Collins, and Ohioan B.H. Eaton (future governor of Colorado) were present, and tried to keep everyone calm. They proposed to appoint some disinterested person for that year to divide water according to the greatest need. That idea was not widely accepted, and the Greeley delegates "hurled defiance in hot and unseemly language." The Fort Collins contingent objected to their uncooperative reaction.
Then the meeting got ugly. Someone stood up and yelled "Every man to his tent! To his rifle and cartridges!"
Eventually, Mr. Eaton and General Cameron were able to quiet the mob, but no solution was found. Luckily, heavy rains the next few days reduced tensions. Irrigators along the Cache la Poudre River soon adopted the principles of the Priority System ("first in time, first in right"). This system had been used in the goldfields of California to reduce bloodshed. Since many irrigators in the region were former gold miners, it was natural they would adopt a similar standard. In addition, miners may have known of the tin miner's water allocation rules in Great Britain. The water rights along the Cache la Poudre River were soon recorded with the Territorial court system. Later in 1876, these irrigators were instrumental in having the "Colorado Doctrine" written into the state constitution:
The right to divert the unappropriated waters of any natural stream to beneficial uses shall never be denied. Priority of appropriation shall give the better right as between those using water for the same purpose.
Surface water development continued throughout Colorado — from the 1800s to the present day. Following the state constitution, the prior person to appropriate, divert, and place water to a beneficial use has a better (more senior) right than someone that diverts later. This system of "first in time, first in right" continues today in Colorado, and most western states, for the allocation of surface water in arid and semi-arid climates.